The ischium has the following landmarks:

Ischial spine - a sharp bony prominence that protrudes from the upper aspect of the posterior border of the bone; serves as an attachment site for the sacrospinous ligament; the ischial spine also serves as a structure that separates two notches formed above and below it:
- Greater sciatic notch - large notch found between the posterior inferior iliac spine and the ischial spine; through this notch passes the piriformis muscle;
- Lesser sciatic notch - relatively small notch between the ischial spine superiorly and the ischial tuberosity inferiorly; the obturator internus muscle goes through this notch;
Ischial tuberosity - massive, blunt and rough area that is found at the posteroinferior corner of the hip bone; it is found at the site where the ischium makes a curve; this landmark serves as an attachment site for such muscles as the semitendinosus, semimembranosus, biceps femoris, and quadratus femoris muscles.

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Ischium (landmarks)